Can I use both of these ports to hard wire devices? I currently have the old version AE behind my TV (wirelessly to the main router) so I can connect my satellite for on-demand and such. I just got a new receiver with network functions that I would also like to connect the same way. Will the WAN and LAN ports on this new AE allow me to do that? Sorry I'm not entirely sure what the WAN is.
If you have configured the new AirPort Extreme to "extend" the wireless network or "join" the wireless network, both Ethernet ports behave as LAN <-> ports, so both can be used to connect Ethernet devices. If you need more ports, add a simple 5-port, 8-port switch, etc for more capacity.
The WAN port would be used to connect to a simple modem if the AirPort Express was configured to be the "main" wireless router on your network.